Dockerfile+
This project provides Dockerfile syntax extensions that have been rejected by the moby project or haven't been addressed in a long time.
Currently, the project adds an INCLUDE+
Dockerfile directive that allows you to import the content of another file into your Dockerfile. There are plans to add more features in the near future.
Getting started
- First, you need to make sure you are running a compatible version of Docker: you need at least Docker 18.09. If you are using an older version, you are out of luck. Sorry!
- Export the following environment variables to enable Buildkit:
DOCKER_BUILDKIT=1
andCOMPOSE_DOCKER_CLI_BUILD=1
(this might not be necessary for newer installations of Docker)
Once your Docker is set, you just need to add the following line as your first line in your Dockerfile:
# syntax = edrevo/dockerfile-plus
That's it!
Features
INCLUDE+
Right now there is just one extra instruction: INCLUDE+
. All Dockerfile+ commands will end up with a +
sign to avoid any potential future collisions with Dockerfile commands.
INCLUDE+
will import the verbatim contents of another file into your Dockerfile. Here's an example Dockerfile which uses the INCLUDE+
instruction:
# syntax = edrevo/dockerfile-plus
FROM alpine
INCLUDE+ Dockerfile.common
ENTRYPOINT [ "mybin" ]
If Dockerfile.common contained a single line that said RUN echo "Hello World"
, then the resulting Docker image would be identical to the one generated by this Dockerfile:
FROM alpine
RUN echo "Hello World"
ENTRYPOINT [ "mybin" ]
Roadmap
The next features in line would be:
ENVFILE+
command, which would read a .env file and import all of those environment variable definitions into the DockerfileRUN+ --no-cache
, which would disable the cache only for a specific RUN step (useful for non-idempotent commands, for example those that clone git repos)TAG
command- improvements to .dockerignore, like recursive dockerignore files
Feedback
Found a bug? Want to contribute a PR? Want to improve documentation or add a cool logo for the project? All contributions are welcome!
Development environment
Install cargo (you can use rustup.rs) and run:
$ cargo build
Creating a local release of the Buildkit frontend
$ docker build -f dockerfile-plus/Dockerfile .